This also limits what we can do on the CPU to manage threads/graphics contexts and frame rate, not to mention keeping of statistics.
I'd really like to get NVIdia to drop the blocking of the CPU in the swapbuffers call, at least as an option for applications that want to have better control in the CPU.
-don
On 10/17/06, Robert Osfield <[EMAIL PROTECTED]> wrote:
Hi Don,
I run with two windows, one on each of my 7800GT cards at a solid 60Hz
without any problems, performance doesn't drop when I run on one card
with one window, to two windows on two cards - the multi-threading all
works pretty smoothly.
I have see the performance drop you talk of when using two windows on
the same graphics card though, is this the problem area you are
thinking of?
Robert.
On 10/16/06, Don Burns < [EMAIL PROTECTED]> wrote:
> I just had a lightbulb go off.
>
> For a long time I've been scratching my head about multi-window performance
> with osg examples. It seemed that whenever I used two windows (or more) the
> performance suffered for no apparent reason. For example, rendering the cow
> (the graphics card equivalent of a drop in the bucket), on a camera
> configration that uses two RenderSurfaces, caused my frame rate to go from
> 60 hz, to 30 hz (or full screen refresh rate to 1/2 screen refresh rate).
>
> I've just realized what that reason is. In a meeting not too long ago with
> Nvidia, I was told that the NVidia driver imposed a block within Swapbuffers
> if you are two frames ahead. I was told that this was done to "maximize
> pipelining" within the graphics chip. I objected to this based on various
> reasons, not the least of which is that I want frame control in the
> application, not in the graphics driver.
>
> So, what is happening here is that for every frame of an application using
> two windows, in which we are issuing Swapbuffers for each window, we are
> being blocked twice waiting for vertical retrace.
>
> Does this ring a bell with anyone else? I need to do some deeper testing
> to confirm this, but it is an issue I'd like to take up with NVidia if the
> ball is in their court here.
>
> -don
>
> _______________________________________________
> osg-users mailing list
> [email protected]
> http://openscenegraph.net/mailman/listinfo/osg-users
> http://www.openscenegraph.org/
>
>
_______________________________________________
osg-users mailing list
[email protected]
http://openscenegraph.net/mailman/listinfo/osg-users
http://www.openscenegraph.org/
_______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
